As will be apparent from German Patent 30 24 432, transporters for workpieces between presses may comprise a first pivotal drive about a vertical axis, a second pivotal drive about a horizontal axis and a generally horizontal cantilever arm which can be so displaced and which may be provided with a linear positioner displaceable horizontally upon this arm and carrying a gripper head which is provided with the gripper hand rotatable or swingable about at least one other axis on the gripper head.
Such workpiece manipulators are utilized widely in the automotive industry and the effect of the linear positioner is to allow the horizontal cantilever arm to have its effective length, i.e. the distance between its gripper head and its horizontal pivot, increased or decreased as required for the proper positioning of the workpiece. The horizontal positioner is generally fixed on the horizontal cantilever arm or is so integrated in it that it can only shift along the linear extent of that arm.
Even with optimum positioning and programming of such a manipulator, because the gripper head cannot be brought closer than a certain distance from the vertical pivot axis of the cantilever arm, the prior art manipulator has been found to be only limitedly successful.